Automatic call distribution (ACD) systems are well-known in the prior art. These systems typically include a switching system for interfacing a plurality of telephone trunk lines to a plurality of agents each located at a workstation. An ACD system provides distribution of incoming calls to those agents who have been available for the longest period of time. The system queues calls on a first-in, first-out basis if no agents are available to handle an incoming call.
Prior art digital switches for use in automatic call distribution systems typically include a control module, a matrix switch, and a plurality of plug-in or "carrier" card modules which provide an interface to the telephone trunks and the agent workstations. The control module is typically connected directly to each of the carrier card modules via a voice bus and a control bus. While such switches have proven generally reliable, it has not been cost-effective in the prior art to provide significant processing capability on the plug-in carrier card modules. Accordingly, in such systems all call processing activities associated with the telephone ports are controlled by information directed via the control bus between the control module and the various card modules. Such "centralized" control of the switching functions decreases the flexibility of the ACD system.
There is therefore a need for an automatic call distribution switching system which obviates such centralized control of switching functions and which provides substantial modularity and distributed processing capability across all levels of the ACD switching system.